THE CONVECTIVE AND ABSOLUTE INSTABILITY OF FLUID FLOW OVER VISCOELASTIC COMPLIANT LAYERS

✍ Scribed by K.S. Yeo; B.C. Khoo; H.Z. Zhao

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 262 KB
• Volume: 223
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1998.2132

✦ Synopsis

The occurrence of waves on viscoelastic compliant layers subject to ¯uid ¯ow is studied from the viewpoint of their classi®cation as convective and absolute instability of the ¯ow-wall system. Uniform potential ¯ow and modi®ed potential ¯ows representing laminar and turbulent boundary layers are considered. It is found that uniform potential ¯ow over viscoelastic (dissipative) layer admits only absolute instability, whereas convective and absolute instability modes may be found under laminar and turbulent boundary layers. The onset velocity of absolute instability remains nearly constant with changes in wall damping, with a value of about 3C t for turbulent boundary layers, where C t is the elastic shear wave speed of the compliant material. Convective instability always occurs at a lower ¯ow velocity than absolute instability. The onset velocity for convective instability, on the other hand, increases fairly rapidly with wall damping and tends towards the onset velocity for absolute instability in the case of a highly damped layer. The results suggest that the static divergence waves observed on highly damped coatings in experiments are manifestation of absolute instability.